The invention is related to the field of slab-coupled optical waveguide lasers (SCOWL), and in particular to a high efficiency SCOWL where the active region of the SCOWL is placed within the interior regions of the SCOWL waveguide, instead of at the edges.
The development of high power, reliable and efficient semiconductor lasers emitting in a single spatial mode has been a challenge for the past few decades.
Earlier demonstrated SCOWL structures required etching through the quantum-well (QW) active region. Etching through the active region eliminates the possibility of lateral current spreading. Current spreading usually causes the laser mode in the SCOWL device to change dramatically as the current spreading becomes more severe under high current injection levels. The problem with etching through the active region, particularly in the AlGaAs/InGaAs/GaAs materials system, is that etching often introduces surface defects at the exposed QW sidewall location. These surface defects propagate into the QW as the device is operated, and the defects can limit the device reliability and operating time since they lead to non-radiative recombination centers.